<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>外边距问题-合并现象</title>
  <style>
    .one1 {
      width: 100px;
      height: 100px;
      background-color: brown;
      margin-bottom: 20px;
    }
    .one2 {
      width: 100px;
      height: 100px;
      background-color: orange;
      margin-top: 50px;
    }
  </style>
</head>
<body>
  <!-- 
    场景: 垂直排列的兄弟元素,上下margin会合并
    现象: 取两个margin值的较大值生效
   -->
  <div class="one1">one</div>
  <div class="one2">two</div>
</body>
</html>